Caesar kaestner



UN ITED STATES PATENT OFFICE.

CAESAR KAES'INER, OF MAGDEBUItG, PRUSSIA, GERMANY.-

PROCESS OF TANNING.

SPECIFICATION forming part of Letters Patent No. 367,145, dated July 26, 1887.

Application filed October 25, 1886. Serial No. 217,164. (No specimens.) Patented in France July 18, 1884, No. 163,381; in England August 19, 1884, No. 11,442; in Germany December 19, 1884, No. 32,282; in Austria-Hungary January 26, 1885, No. 4,341 and No. 2h,174; in Belgium January 28, 1885, No. 67,682, and in Canada December 11, 1885, No 24,549.

To all whom it may concern.-

Be it known that I, OAEsAR KAESINER, a subject of the King of Prussia, German Em pire, and aresident of Magdeburg, in the Kingdom of Prussia, Empire of Germany, have invented a new and useful Improvement in Tanning Leather, (for which I have obtained patent in France the 18th of July, 1884, No. 163,381; in England the 19th of August, 1884, No. 11,442; in Germany the 19th of December, 1884, No. 32,282; in Belgium the 28th of January, 1885, No. 67,682; in Austria-Hungary the 26th of January, 1885, No. 4,841 and No. 26,174, and in Canada the 11th of December, 1885, No. 24,549,) of which the following is a specification.

Heretofore leather has been tanned either by dressing it with alum or preparing it with tan. In the former case it is treated with alum. In the latter case the raw unhaired leather is treated with tan, tannic acid, or any other tanning substance that operates similarly; but the two methods have never been combined as yet-that is to say, leather has never been first dressed with alum and afterward treated with tan, tannic acid, or other tanning substances. The reason of this is that this combined process cannot be carried out under ordinary circumstances. This combined process is not possible unless two conditions are adhered to, and these two peculiar conditions are as follows: First, when the leather has been dressed with alum it must be dried thoroughly before being subj ected to the second process; secondly, water must not be used in the second process, and in the place of it alco readily tanned and with all good qualities in the short space of three weeks, whereas heretofore tanning has occupied no less than one to two years.

My invention is carried into efiect in the following manner: The skins are kept in water one day or two, and are then put into asolution of lime, sulphuret of sodium, and water, and in this solution they remain for two or three days. They are then. unhaired, (pared,) delimed, (the limed is removed,) and put into an infusion of wheat-bran and water. When taken out of this infusion, the skins are placed ina solution of four parts of alum and one part of salt with water, and are kept in it from one to four days, according to their thickness, and till the cellular texture is impregnated with the solution. They are then hung up to dry, stretched, and when quite dry are laid into a solution of eighty parts of alcohol and twenty parts of tannic acid. This tannic acid may consist of tannin, guebcacho, catechu, &c. Twenty parts of each separately may be used, or the twenty parts may consist of several of these acids. It is best to put this solution of tannic acid in a cask made to rotate and provided with a lid that closes hermetically. \Vhen the skin has been put in, the cask is turned a few times every day. In the short space of one to six days the cellular texture of the skin will have absorbed the tannic acid, and the skin is then ready for further treatment. The skin is then washed in the fulling-tub with warm water, by means of which the alum contained in the skin is removed. It is hereafter laid in a solution of pinic acid and water, which gives it a fine light color. The tanning process is then finished, and the skin can be used for any sort of leather.

What I claim,and desire to secure by Letters Patent of the United States, is-

In the tanning of leather, the combined process consisting in dressing the leather withalum first, then drying it thoroughly, and finally treating it with tannin, which is dissolved in rectified alcohol, for the purpose mentioned, and as described. i

In witness whereof I have hereunto set my hand in presence of two witnesses. CAESAR KAESTNER.

Witnesses:

OTTO SAMBERG, W. ScHUBERT. 

